/*
 * -\-\-
 * Mobius
 * --
 * Copyright (c) 2017-2020 Spotify AB
 * --
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * -/-/-
 */
package com.spotify.mobius;

import javax.annotation.Nonnull;

/**
 * An interface representing the Update function used by Mobius for performing model transitions and
 * requesting side-effects.
 *
 * <p>Implementations of this interface must be pure - they should have no model and no
 * side-effects. This means that given the same arguments, the function must always return the same
 * Next. Each time a new event occurs, the update method will be called and a Next is expected.
 */
public interface Update<M, E, F> {

  @Nonnull
  Next<M, F> update(M model, E event);
}
